A cleaning apparatus for toner image transfer type electrophotographic copying machines and the like, as seen in FIG. 1a, is provided with a blade 2 for scraping toner particles T, which may remain on the surface of a photoconductive drum 1, i.e. the member to be cleaned, after development, from the drum. Most of these particles are allowed to fall away from the drum and then they are recovered. However, when the cleaning apparatus is operated for a prolonged period of time, toner particles T progressively accumulate on the blade 2 at a location close to its forward edge, as illustrated in FIG. 1a, and the deposit of accumulated toner particles T is liable to form a solid mass or agglomerate under the influence of ambient conditions (temperature and humidity). Further if a large quantity of residual toner particles T are present at the forward edge of the blade 2, the force from the rotation of the drum 1 and the pressure of the blade 2 in contact therewith will act to agglomerate the toner particles T at the location where the forward edge of the blade is in contact with the drum surface as shown in FIG. 1b.
The agglomerates of toner particles T thus formed are likely to engage in the clearance between the blade edge and the drum surface, giving rise to improper cleaning or causing damage to the drum surface. With copying machines wherein the residual toner is reused for development, another problem is encountered, namely that such agglomerates tend to clog up the toner transport system or produce black spots on toner images.
Further if extraneous particles P, such as paper particles, lint or like coarse dust particles, are present on the drum surface along with residual toner particles, these extraneous particles P will gradually accumulate at the location where the forward edge of the blade is in contact with the drum surface, eventually pushing the blade edge locally up out of proper pressing contact with the drum surface, resulting in the problem that the blade fails to scrape off the residual toner completely.
To overcome these problems, a method has been proposed in U.S. Pat. No. 3,859,691 for removing toner particles and extraneous matter from the edge of a blade with a jet of air, and U.S. Pat. No. 4,158,498 discloses a system for removing toner particles from an edge of a blade by a stationary cleaning brush when the blade is moved away from an imaging surface.
However, the former method has the drawback that the cleaning apparatus is large sized and expensive, while the latter system involves the disadvantage that the removed toner will stain the blade again and consequently stain the imaging surface.
Another apparatus has been proposed in U.S. Pat. No. 3,781,107 wherein a blade in the form of an endless belt is revolved so that two segments of the blade are alternately used for cleaning, and when the blade is revolved for changing the segments used for cleaning, toner particles and extraneous matter are removed from an edge of the unused segment by a brush.
This apparatus has the drawback of necessitating a special arrangement for the alternate use of the blade segments.
Still another apparatus has been proposed in Published Unexamined Japanese Utility Model Application No. Sho 53-150231 which includes a rotary brush and a blade both adapted to remove residual toner particles and extraneous matter from the surface of a photoconductive drum and in which the forward edge of the blade is cleaned by the rotary brush.
Although it is free of the drawbacks experienced with the other proposed apparatus, this apparatus has difficulty in completely removing toner particles from the blade edge with the rotary brush because it is difficult for the ends of the bristles of the brush to come into full contact with the blade edge which is in pressing contact with the drum surface or to effectively perform the function of removing toner particles even if they are in contact with the blade edge. The rotary brush is therefore unable to remove the toner particles from the blade edge if they are deposited thereon in the form of agglomerates as described with reference to FIG. 1b. Furthermore, the agglomerates of toner particles engaging in the clearance between the blade edge and the drum surface cannot be removed by the rotary brush.